Conventional apparatus utilized to cool electronic components while in use in aerospace, aviation, laser apparatus and military applications are often unsatisfactory. Conventional apparatus fail to provide an adequate conductive heat path and convective heat transfer systems for the cooling of electronic components.
As machinery in these industries continues to evolve by becoming smaller, having increased power requirements and/or more complicated, the need has developed for additional electronics and higher capacity processing of electronic components. Higher capacity processing and additional electronics associated with more sophisticated machinery has led to increased thermal waste in the form of heat. In addition, current electronics and higher capacity processors have been sized down to fit into smaller equipment with limited space for cooling. Advancements in these industries drive the search for more efficient ways to dissipate heat and maintain the electronics at optimal temperatures.
In order to facilitate the discovery of novel apparatus and methods for improved cooling and thermal dispersement, it is important to understand the “science” behind the process of cooling in these applications. Adequate heat exchange of electronic components depends on the steady, low resistance contact between the component(s) generating the heat or thermal energy and the surrounding components, modules or space. In the industries mentioned earlier, some of the more critical cooling challenges are found when investigating the thermal path between electronic components, generally found on a module frame, and a heat spreader or heat sinking device that is coupled to or near the electronic component. In this example, the pathway for heat exchange includes attachment or coupling of the module frame to a card rail. A liquid or air cooled heat spreader or heat sinking device is also attached or integrated into the pathway. The module frame may be directly attached to a card rail by an integrated retainer, or coupled to the card rail by a retainer that couples the module frame to the card rail through the application of variable force.
As shown in U.S. Pat. No. 4,819,713, a conventional retainer 100 (Prior Art FIG. 1A) referred to as a “Card-LOK” retainer is disclosed. This “stand alone retainer” provides heat exchange using a device having a screw (not shown) that passes through the entire retainer, which comprises a front wedge segment 110, a center body segment 120 and a rear wedge segment 130—all of which have a threaded hole (not shown). The wedge segments have a trapezoidal configuration with angled ends that allows them to move in relation to one another. The retainer is then coupled to the module frame. The screw is designed to move and reposition the wedge segments with respect to one another to produce, in some instances, a staggered configuration. The screw is also designed to lock the module frame in place through the expansion of the retainer up against the module frame. This contact provides a contact between the module frame and the card rail incorporating the heat sinking device. Heat or thermal energy generally travels a path from the module frame to the one adjacent coldwall and not through the retainer and to the heat sinking device. This path isn't adequate, since heat and thermal energy will be released into the overall system, which can potentially create overheating of other components and ultimately a shut down of the entire system.
One problem with the heat transfer system or wedge system described above is that heat must move through the shear regions of the retainer segments (blocks). These types of retainers tend to use open cavity extrusions that rely on tangential contact to create the wedge-segment displacement. Heat transfer must also traverse these interfaces for conductive heat sinking. Laboratory evaluation has shown that the contact between shear planes (segments) occurs as ‘point’ contact or near point contact, since the wedges do not displace sufficiently in the normal direction relative to the heat conducting surfaces. Another result of this non-uniform wedge displacement is that thermal contact to the heat sinking device tends to occur as a point contact or near point contact (see reference number 230) (see Prior Art FIG. 1B). Prior Art FIG. 1B shows a contact map 210 between a conventional wedge retainer (not shown) and a cold wall interface 220 at 325 pounds reaction force. Given that the contact surface area is a key component of any good thermal displacement system, these conventional retainers do not perform to the standards that are currently needed.
Another consideration is that the aerospace industry cannot rely upon convective heat transfer as an efficient method for dissipating heat, primarily because of the vacuum atmosphere in space or high altitude for aircraft. Accordingly, aerospace components generally rely upon conductive heat transfer during use to dissipate heat. Conventional retainers that effectively create point or near point contacts will significantly limit heat transfer, and therefore, it is likely that electronic components and other sensitive parts near the thermal source will be damaged or destroyed.
Therefore, there is a need in the aerospace, aviation and other related industries to produce a retainer, and ultimately a retainer/module system, that addresses at least one of the following goals: a) provides a continuous conductor path through the retainer, b) provides an increased and near complete contact surface area between the retainer and the component to which it is coupled or attached, c) can fit easily within conventional systems without any need for a redesign of the other components, d) can be manufactured utilizing any suitable thermal transfer material or constituent, e) provides a complete contact surface area between the retainer and the component to which it is coupled or attached in a range of temperatures, including cold, cool, warm, hot or very hot, and f) can improve both the convective and conductive transfer of heat over conventional retainers and heat transfer devices.